Double-Pole Approximation in Time-Dependent Density Functional Theory

TL;DR

This paper introduces a double-pole approximation in TDDFT to better understand strong exchange-correlation effects, revealing how interactions can suppress certain optical transitions.

Contribution

It extends the single-pole approximation to a two-pole model, providing new insights into strong-coupling effects in TDDFT.

Findings

Interaction can cause a transition to vanish from the optical spectrum

The double-pole approximation illustrates strong exchange-correlation effects

Provides a simple analytical approach to complex TDDFT phenomena

Abstract

A simple approximate solution to the linear response equations of time-dependent density functional theory (TDDFT) is given. This extends the single-pole approximation (SPA) to two strongly-coupled poles. The analysis provides both an illustration of how TDDFT works when strong exchange-correlation effects are present and insight into such corrections. For example, interaction can cause a transition to vanish entirely from the optical spectrum.